Gold Nanoparticle-Containing Membranes from in Situ Reduction of a Gold(III)-Aminoethylimidazolium Aurate Salt

The first example of polycarbonate membranes (PC) modified using layer-by-layer (LBL) adsorption of a polyelectrolyte(PE)/AuNPs system [PE = poly(ethylene-imine), PEI; poly(acrylic acid) sodium salt, PAA] in which the AuNPs formation occurs via the in situ post-deposition reduction of the incorporated novel gold(III)-aminoethyl imidazolium aurate salt [Cl3AuNH2(CH2)2ImMe)][AuCl4] (1) is reported. The reduction of 1, to give gold nanoparticles stabilized by an amino-functionalized ionic liquid (ILNH2-AuNPs), was carried out either by the PAA itself during the LBL deposition or by the combined action of PAA and Ascorbic Acid, the latter added at the end of the deposition process. The different membranes were characterized with AFM, SEM, TEM, UV-Vis and XRD. The XRD analysis revealed that the presence of ILNH2 caused a remarkable increase of gold nanoparticles with (111) planes parallel to the PC film. The catalytic activity of the modified membranes in the reduction of 4-nitrophenol to 4-aminophenol by NaBH4 was investigated and found higher than membranes modified with preformed citrate-stabilized gold nanoparticles (citr-AuNPs) solutions.